diff --git a/join.c b/join.c
index b2fd07e..f682023 100644
--- a/join.c
+++ b/join.c
@@ -29,6 +29,7 @@ struct field {
 
 struct line {
 	char *text;
+	size_t len;
 	size_t nf;
 	size_t maxf;
 	struct field *fields;
@@ -152,9 +153,7 @@ prjoin(struct line *la, struct line *lb, size_t jfa, size_t jfb)
 static void
 prline(struct line *lp)
 {
-	size_t len = strlen(lp->text);
-
-	if (fwrite(lp->text, 1, len, stdout) != len)
+	if (fwrite(lp->text, 1, lp->len, stdout) != lp->len)
 		eprintf("fwrite:");
 
 	putchar('\n');
@@ -218,6 +217,7 @@ makeline(char *s, size_t len)
 
 	lp = ereallocarray(NULL, INIT, sizeof(struct line));
 	lp->text = s;
+	lp->len = len;
 	lp->fields = ereallocarray(NULL, INIT, sizeof(struct field));
 	lp->nf = 0;
 	lp->maxf = INIT;